The present invention relates to a system and method for determining a protection level, and more particularly, to a protection level determination system and method that calculate a protection level to which an adjustment coefficient is applied. An aircraft navigation system is required to acquire a position solution that may satisfy high levels of accuracy, integrity, continuity, and availability in order to perform navigation such as access and landing.
When a Global Navigation Satellite System (GNSS)-based navigation system is used alone, its performance is not sufficient. Accordingly, the performance can be improved by using augmentation systems such as a Ground Based Augmentation System (GBAS) and a Satellite Based Augmentation System (SBAS).
Since the SBAS transmits augmentation information through a signal similar to that of the GNSS broadcasted by a geostationary satellite, the SBAS may be easily utilized by an aviation user as well as the users of the GNSS in various fields.
Also, the SBAS may provide relatively uniform performance to users located in a large area and thus may be utilized in various ways.
However, an SBAS receiver for aviation calculates a protection level using integrity parameters broadcast by the SBAS in order to check availability of a position solution of the SBAS.
The protection level is a value for predicting a position error after applying SBAS augmentation information. Only when the protection level is within an allowable error level needed for performing a specific aviation task, safety is guaranteed. Thus, the position solution may be used for aviation.
In this case, in order to satisfy strict integrity requirements for its use for aviation, the SBAS transmits integrity parameters very conservatively with an assumption of the worst conditions that affect all error factors.
Thus, a user of the SBAS may obtain a very high protection level, compared to a position error that is actually experienced in a typical situation.
Accordingly, the provision of a protection level calculated according to requirements for aviation to a user who is not an aviation user does not consider the user's need, thus causing great damage to the user in terms of availability.